Disease
“Is it catching?” People
sometimes ask this question when they hear that someone is sick. They are
talking about a kind of human disease. The kinds of diseases that are contagious
(catching) are caused by microscopic germs. Diseases caused by germs are called
infectious diseases. Other human diseases can be caused by many things.
WHAT
DISEASES DO GERMS CAUSE?
Pneumonia, strep throat,
and food poisoning are some of the diseases caused by germs called bacteria.
Bacteria are living things made of just one cell.
Germs called viruses cause
colds, chicken pox, flu, mumps, measles, polio, and AIDS. Viruses are even
tinier than bacteria.
A germ called a fungus
causes athlete’s foot. Malaria is caused by a germ called a protozoan.
Protozoans are made of one cell and are like tiny animals. Mad cow disease may
be caused by a strange bit of protein called a prion.
HOW
DO GERMS SPREAD?
Many germs spread in coughs
and sneezes. Sick people get these germs on their hands. You can pick up these
germs by touching a doorknob or something else that a sick person touched.
Washing your hands regularly can help keep you safe from many diseases caused
by germs.
Long ago, many people
in Europe and North America died from diseases called cholera and typhoid. The
germs that cause these diseases live in dirty water. Good sewers and clean
water stopped the spread of these diseases in many countries. These diseases
are still a problem in poor countries.
WHAT
ELSE CAUSES DISEASE?
Contact with poisons can
cause disease. Smoking tobacco can cause lung cancer and other lung diseases.
Drinking lots of alcohol can damage the brain and liver. Lead in drinking water
or paint can cause mental problems in children.
Clogged blood vessels
cause heart disease. Many older people get diseases caused by body parts
wearing out. Arthritis, Parkinson disease, and Alzheimer’s disease are diseases
that most often occur as people age.
Sometimes, babies are
born with diseases or birth defects. Sometimes babies can inherit (get
from their parents) a disease that occurs later in life. Diabetes, high blood
pressure, and muscular dystrophy are diseases that people can inherit.
Some diseases are caused
by the body’s disease-fighting system. This system is called the immune system.
Allergies come from the immune system fighting too much. Touching poison ivy
can cause an itchy rash. The rash is a sign of an allergy.
Asthma is a breathing
problem caused by the immune system. People can die from a bad asthma attack.
Not eating the right foods
can cause disease. Not having enough vitamins can cause some diseases. A lack
of vitamin C causes scurvy. Scurvy makes the skin bleed and teeth fall out.
Hundreds of years ago, sailors on long voyages often died of scurvy.
WHAT
ARE THE SIGNS OF DISEASE?
Chills and fever are often
signs of diseases that are caused by germs. Pain can be a sign of disease. A
diseased appendix or other organ causes pain. Itchy eyes and a runny nose can
be a sign of hay fever or other allergy. Trouble breathing can be a sign of
asthma.
Some diseases have no
signs that you can see or feel. You cannot see or feel high blood pressure.
Some diseases can only be found during a physical exam by a doctor. It is
important to have regular checkups.
HOW
DO DOCTORS TREAT DISEASES?
Doctors treat many kinds
of diseases with medicines. Doctors can kill most disease-causing bacteria with
drugs called antibiotics. Doctors give drugs to lower high blood pressure.
Doctors cannot really
cure diseases caused by viruses. Your body can fight off colds and flu. The
body cannot fight off AIDS, polio, and some other diseases caused by viruses.
Doctors have drugs that can slow the AIDS virus. Doctors can vaccinate you
against some diseases caused by viruses. Vaccinations help your body fight off
disease. There are vaccines against chicken pox, flu, measles, polio, and some
other viruses.
Doctors treat some diseases
with surgery. They use surgery to take out diseased organs or tumors.
Some diseases doctors
cannot yet cure or even treat. Researchers in laboratories are looking for ways
to help people with these diseases.
Doctors tell people it
is best to keep from getting diseases. Getting plenty of sleep and exercise and
eating the right foods can help keep you healthy.
